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Docs: Less leading backslashes

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Krystine Sherwin 2024-05-27 16:02:17 +12:00
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16
docs/source/using_yosys/synthesis/fsm.rst
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@ -19,24 +19,24 @@ FSM detection
~~~~~~~~~~~~~ ~~~~~~~~~~~~~
The `fsm_detect` pass identifies FSM state registers. It sets the The `fsm_detect` pass identifies FSM state registers. It sets the
``\fsm_encoding = "auto"`` attribute on any (multi-bit) wire that matches the ``fsm_encoding = "auto"`` attribute on any (multi-bit) wire that matches the
following description: following description:
- Does not already have the ``\fsm_encoding`` attribute. - Does not already have the ``fsm_encoding`` attribute.
- Is not an output of the containing module. - Is not an output of the containing module.
- Is driven by single `$dff` or `$adff` cell. - Is driven by single `$dff` or `$adff` cell.
- The ``\D``-Input of this `$dff` or `$adff` cell is driven by a multiplexer - The ``D``-Input of this `$dff` or `$adff` cell is driven by a multiplexer
tree that only has constants or the old state value on its leaves. tree that only has constants or the old state value on its leaves.
- The state value is only used in the said multiplexer tree or by simple - The state value is only used in the said multiplexer tree or by simple
relational cells that compare the state value to a constant (usually `$eq` relational cells that compare the state value to a constant (usually `$eq`
cells). cells).
This heuristic has proven to work very well. It is possible to overwrite it by This heuristic has proven to work very well. It is possible to overwrite it by
setting ``\fsm_encoding = "auto"`` on registers that should be considered FSM setting ``fsm_encoding = "auto"`` on registers that should be considered FSM
state registers and setting ``\fsm_encoding = "none"`` on registers that match state registers and setting ``fsm_encoding = "none"`` on registers that match
the above criteria but should not be considered FSM state registers. the above criteria but should not be considered FSM state registers.
Note however that marking state registers with ``\fsm_encoding`` that are not Note however that marking state registers with ``fsm_encoding`` that are not
suitable for FSM recoding can cause synthesis to fail or produce invalid suitable for FSM recoding can cause synthesis to fail or produce invalid
results. results.
@ -44,7 +44,7 @@ FSM extraction
~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~
The `fsm_extract` pass operates on all state signals marked with the The `fsm_extract` pass operates on all state signals marked with the
(``\fsm_encoding != "none"``) attribute. For each state signal the following (``fsm_encoding != "none"``) attribute. For each state signal the following
information is determined: information is determined:
- The state registers - The state registers
@ -109,7 +109,7 @@ The `fsm_opt` pass performs basic optimizations on `$fsm` cells (not including
state recoding). The following optimizations are performed (in this order): state recoding). The following optimizations are performed (in this order):
- Unused control outputs are removed from the `$fsm` cell. The attribute - Unused control outputs are removed from the `$fsm` cell. The attribute
``\unused_bits`` (that is usually set by the `opt_clean` pass) is used to ``unused_bits`` (that is usually set by the `opt_clean` pass) is used to
determine which control outputs are unused. determine which control outputs are unused.
- Control inputs that are connected to the same driver are merged. - Control inputs that are connected to the same driver are merged.

2
docs/source/using_yosys/synthesis/opt.rst
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@ -196,7 +196,7 @@ Removing unused cells and wires - `opt_clean` pass
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This pass identifies unused signals and cells and removes them from the design. This pass identifies unused signals and cells and removes them from the design.
It also creates an ``\unused_bits`` attribute on wires with unused bits. This It also creates an ``unused_bits`` attribute on wires with unused bits. This
attribute can be used for debugging or by other optimization passes. attribute can be used for debugging or by other optimization passes.
When to use `opt` or `clean` When to use `opt` or `clean`